Field of the Invention
The invention is related to a wireless communication device and a filter thereof, and more particularly to a wireless communication device with concurrent dual-radio operation and a filter thereof.
Description of Related Art
For the past few years, wireless local area network that meets IEEE 802.11 ac communication standard utilizes concurrent dual-radio technology to increase the number of user connections. The IEEE 802.11ac communication standard may use the band of unlicensed national information infrastructure (UNII) to perform communication. With concurrent dual-radio operation, two transceivers in a wireless communication device may simultaneously operate in an UNII-1(5.17˜5.25 GHz) band and an UNII-3(5.735˜5.815 GHz) band adjacent to each other. In addition, to prevent the wireless communication device from being affected by the interference between two bands, it is necessary to equip the wireless communication device with a filter having a steep filtering curve and high isolation.
Generally speaking, a thin-film bulk acoustic resonator (FBAR) and a dielectric resonator filter (DRF) are often used to be designed as a filter having a steep filtering curve or high isolation. However, the above filter has to be manufactured through a special process; therefore, the manufacturing cost is high and the filter is formed to have a large area. Additionally, conventional technologies increase order of the filter to increase the attenuation thereof. However, as the order of the filter increases, the size of the filter increases as well, causing the filter to have larger insertion loss and worse amplitude flatness. In other words, conventional filters normally increase the manufacturing cost of the wireless communication device and limit minimization of the wireless communication device.